The complexities of golf club design are known. The specifications for each component of the club (i.e., the club head, shaft, grip, and subcomponents thereof) directly impact the performance of the club. Thus, by varying design specifications, a golf club can be tailored to have specific performance characteristics. Among the more prominent considerations in club head design are loft, lie, face angle, horizontal face bulge, vertical face roll, center of gravity, rotational moment of inertia, material selection, overall head size, and overall head weight.
Golfers need golf clubs that can be used to hit the ball the right distance in the intended direction and enjoy the game more when the golf clubs have been customized and personalized to match their abilities and preferences. There have been attempts to offer golfers the ability to adjust and customize their golf clubs. Some attempts include adjustable weight systems, adjustable loft or lie angles, means to attenuate sound, and personalization. Those clubs are fraught with problems because the adjustment mechanisms interfere with aerodynamics, collect dirt and grime, have small parts that break when they hit the ground during use, and are difficult to use.
Some attempts have been made to put weights inside of golf clubs. For example, U.S. Pub. 2008/0261715 to Carter shows a golf club head with tracks and weights. U.S. Pat. No. 8,206,243 to Stites reports a moveable weight member in a golf club head. U.S. Pub. 2013/0260913 to Beach shows a club head with a track with a weight. U.S. Pub. 2013/0296070 to Stites shows a club head with face-aft weight slot in the sole. There have further been attempts to provide removable covers for providing access to the club interior for placement of weight inside the golf club. For example, U.S. Pat. No. 8,491,413 to Billings reports a hollow-body golf club head with a removable weighting port providing access the interior of the club head and placement of a weighting material. Unfortunately, some weight systems break during use. Furthermore, external adjustment mechanisms are complicated to use, fragile, and adversely affect inertial properties. Additionally, removable covers for providing access to the interior of the club head may have a negative effect on other club head performance characteristics, including the sound of the club head upon impact with the ball.
Another important aspect of club head design includes consideration of the sound created upon impact between the club head with a ball. Golfers have become accustomed to hearing a particular sound when the golf club impacts the golf ball, especially when a large volume golf club is used. This “ideal sound”, although often a result of personal preference, can drastically turn into an unappealing sound if it varies too much from the above mentioned “ideal sound.”
For example, as the size of golf club heads has increased, weight distribution has become a major design consideration. In particular, in the quest to design in additional discretionary mass, it has become desirable to decrease the wall thicknesses of the portions of the club head wall that do not improve mass properties. Additionally, composite materials have also been used in the past to replace various sections of the club head walls to further improve weight distribution and generate discretionary mass. Furthermore, some club heads include removable covers placed on different portions of the club head body, wherein the removable cover is generally flat and has a low inherent natural frequency. Because of the thin walls, composite materials, shapes/contours of removable covers, and/or the large volumes of the golf club head, large portions of the heads act as membranes and vibrate relative to each other. In some instances, the vibration that takes place could result in an unappealing sound during impact between the golf club and the golf ball.